endforeach( mylibfolder )
-if (NOT SIMGEAR_HEADLESS)
+if(NOT SIMGEAR_HEADLESS)
add_subdirectory(environment)
add_subdirectory(screen)
add_subdirectory(scene)
add_subdirectory(sound)
-endif()
+endif(NOT SIMGEAR_HEADLESS)
+if(ENABLE_RTI)
+ add_subdirectory(hla)
+endif(ENABLE_RTI)
+
set(HEADERS compiler.h constants.h sg_inlines.h ${PROJECT_BINARY_DIR}/simgear/version.h)
install (FILES ${HEADERS} DESTINATION include/simgear/)